There has been known an electronic control unit in which electronic components including MOSFETs, which receive power and thus generate heat, are mounted on a substrate having an interconnection pattern. An electronic control unit of JP2010-245174A includes a heat sink on one side in a thickness direction of a substrate and a metal cover on the other side. Heat generated by the electronic components is radiated to the heat sink and to the cover.
However, the electronic control unit described in JP2010-245174A employs the metal cover, which thus leads to issues of large weight and high production cost.